Noisy Blower Fan

[spako]

This evening the blower fan in my C5 became very noisy with annoying high pitch sound (the faster fan setting the higher pitch sound). When I switch the blower off, it's nice and quiet.

Am I right thinking that the fan bearing is at fault?

Or perhaps some dirt got in there?

Any idea how do I go about fixing this?

[spako]

After driving a while, the noise seems to be gone. It must have been some kind of dirt/leaf causing the noise.